# CVE-2026-48108: Eugeny Russh resource exhaustion in SSH identification parsing

Source: https://junglewise.ai/threats/cve-2026-48108-eugeny-russh-resource-exhaustion-in-ssh-identification-parsing  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-10. Updated: 2026-06-11  
License: CC BY 4.0 with a link back

CVE-2026-48108 · Severity: medium · CVSS 5.3 · Published 2026-06-10

Russh is a library used to implement SSH servers and clients in the Rust programming language. A vulnerability in how the library handles initial connection messages allows a remote attacker to send an unlimited number of invalid lines before identifying themselves. This can be used to consume server resources and keep connections open indefinitely, potentially leading to a denial of service for legitimate users.

Technologies: [russh (crates.io)](https://junglewise.ai/threats/technologies/crates-io-russh), [Eugeny Tabby](https://junglewise.ai/threats/technologies/tabby). Vendors: [crates.io](https://junglewise.ai/threats/vendors/crates-io), [Eugeny](https://junglewise.ai/threats/vendors/eugeny).

## Quick answers

**Is CVE-2026-48108 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-48108 being exploited in the wild.

**How severe is CVE-2026-48108?** Medium severity, with a CVSS score of 5.3, published 10 June 2026.

**Which products and versions are affected?** russh (crates.io) SEMVER:introduced=0.34.0-beta.1,fixed=0.61.0; Eugeny Tabby >= 0.34.0-beta.1, < 0.61.0.

**Is there a fix for CVE-2026-48108?** Yes. russh (crates.io): upgrade to 0.61.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-48108 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-48108?** Check whether you run russh (crates.io) or Eugeny Tabby at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- russh (crates.io): upgrade to 0.61.0 or later

  ```sh
  cargo update -p russh
  ```


## Technical details

The russh library's identification reader (read_ssh_id) failed to enforce RFC 4253 requirements for server-side parsing. Specifically, it used the same permissive logic for both clients and servers, allowing clients to send pre-banner lines that should only be permitted from servers. Furthermore, the parser did not implement a limit on the number of pre-banner lines or strict line length limits. An unauthenticated remote attacker can exploit this by sending a continuous stream of non-SSH lines, keeping the connection in a pre-authentication state and consuming server resources. The vulnerability also functions as a parser-state oracle, allowing for cheaper fingerprinting of the server's parser behavior. The issue is fixed in version 0.61.0 by introducing stricter client-identification reading and explicit line count/length limits.

## Affected products

- Eugeny russh >= 0.34.0-beta.1, < 0.61.0

## Identifiers

- CVE-2026-48108
- GHSA-76r6-x97p-67vr

## Timeline

- 2026-05-20: disclosed
- 2026-06-10: advisory: NVD publication date
- 2026-06-11: patched: Version 0.61.0 released

## References

- [https://api.github.com/users/mjc](https://api.github.com/users/mjc)
- [https://github.com/mjc](https://github.com/mjc)
- [https://api.github.com/users/mjc/gists%7B/gist_id%7D](https://api.github.com/users/mjc/gists%7B/gist_id%7D)
- [https://api.github.com/users/mjc/repos](https://api.github.com/users/mjc/repos)
- [https://avatars.githubusercontent.com/u/1977?v=4](https://avatars.githubusercontent.com/u/1977?v=4)
- [https://api.github.com/users/mjc/events%7B/privacy%7D](https://api.github.com/users/mjc/events%7B/privacy%7D)

## Related threats

- [russh SSH server signature algorithm mismatch in publickey auth](https://junglewise.ai/threats/cve-2026-111062-a-russh-ssh-server-accepts-a-publickey-authentication-whose)
- [russh SSH agent confirmation bypass](https://junglewise.ai/threats/cve-2026-116794-russh-is-a-rust-ssh-client-and-server-library-that-includes-an)
- [russh SSH library zero maximum packet size denial of service](https://junglewise.ai/threats/cve-2026-116774-russh-is-a-rust-ssh-client-and-server-library-that-includes-an)
- [russh memory exhaustion via unbounded EXT_INFO packets](https://junglewise.ai/threats/cve-2026-116773-russh-is-a-rust-ssh-client-and-server-library-that-includes-an)
- [russh's SSH agent server is susceptible to unbound allocations via repeated SSH_AGENT_CONSTRAIN_CONFIRM messages](https://junglewise.ai/threats/cve-2026-116696-russh-is-a-rust-ssh-client-and-server-library-that-includes-an)